Electron discharge device and circuit



May 21, 1940. J. L. H. JONKER ELECTRON DISCHARGE DEVICE AND C IRCUIT Filed Dec. 17, 1938 INVENTOR. L/OHAN L. H. JONKER ww=w A TTORNEY.

Patented May 21, 1940 UNITED STATES PATENT orrics ELECTRON DISCHARGE. DEVICE AND CIRCUIT Application December 17, 1938, Serial No. 246,289 In the Netherlands January 8, 1938 Claims.

This invention relates to an electron discharge device and a circuit arrangement for obtaining a variable mutual conductance.

For obtaining a variable mutual conductance, 5 use is generally made of tubes having grids of irregular form, various parts of which are wound, for example, with different pitches. The disadvantage that may sometimes be inherent in such construction is, however, that the variable mu characteristic is constituted by a number of characteristics of different mutual conductance obtaining for the various separate grid parts so that irregularities may arise.

It is the principal object of the invention, to provide an improved tube and circuit having characteristics which permit a continuous change in mutual conductance.

The invention is based on the recognition of the fact that if two grids are so arranged that their active parts are substantially equidistant from the cathode it is possible to obtain a variable mu characteristic. It is known to arrange grids so as to be located in one plane, consequently having their windings arranged between one an- 25 other, inter alia for obtaining a mixing action, the grids being controlled by different frequencies. It is also known to remove disturbances by means of such a construction by controlling one of the grids in antiphase by means of the disturbing frequency.

According to the invention, use is made of a circuit arrangement which permits obtaining a regulable mu characteristic by means of a tube containing at least two grids the active parts of which are immediately adjacent each other, by supplying the control voltage to these grids jointly, these grids being, however, connected in part to a fixed and in part to a variable bias.

These grids may be entirely uniform but it may 40 be of advantage to build up one of the grids in thicker wires than the other so that the influence of the controlling action of this grid is intensified. Although it is not necessary it has been found advantageous to arrange the active 5 parts of the grids in one plane or common surface, that is to say equidistant from the oathode. Since these grids have the control voltage supplied to them jointly it is, of course, desirable that they should have a practically equal distance relatively to the cathode and the other electrodes. It is, however, also possible to wind the grids withabout the same diameter so as to enable them to enclose each other exactly.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best beunderstood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a diagrammatic showing of a tube made according to my invention and its associated circuit, Figures 2 to 5 inclusive are side and end views of portions of two different grid constructions made according to my invention.

Referring to Figure 1, the cathode has around it grids 2 and 3 located in one plane, a screening grid i and an anode 5 connected to the output circuit 8.

According to the invention, the grids 2 and 3 have the control voltage supplied to them for example by means of the input circuit 2, through coupling condensers 8 and 9, Whereas the negative bias is supplied to the grids 2 and 3 through leaks it! and i l, the fixed voltage which in this case is placed on the grid 3 being governed by the cathode resistance l2 which is bypassed by the condenser i3.

The grid 2 has the control voltage for the variable mu supplied to it, which in this case is effected by means of a variable resistance Hi, shunted by a condenser l5. It is, however, also possible to obtain this voltage automatically in known manner. According as the grid 2 becomes negative to a higher extent, the flow of electrons which passes between the various grid-wires will be compressed more and more in the direction of the active parts of the grid 3 since the electrostatic field of the latter grid does not vary. The penetration and predomination of the field of grid 2 in the field of grid 3 will consequently proceed slower according as it approaches to the active parts of grid 3. Consequently, the more the negative grid voltage on the grid 2 increases, the more the mutual conductance will be decreasing. This decrease in mutual conductance consequently proceeds in a very uniform manner in contradistinction to what is often the case with the well-known constructions in which irregularly wound grids are used.

Since the two grids of a tube according to the invention, if their active parts are located in one plane, constitute jointly one quite regularly wound grid it is also possible to use a tube of this kind in circuit arrangements in which a constant mutual conductance is desired.

The screening grid 4 may be connected through a resistance I6 which is by-passed by a condenser ll.

The grids may be shaped, for example, in the form shown in Figures 2 and 3. The grid wires l8 and I9 are respectively secured to the supporting wires 20 and 2|. As may be seen from Figure 3, the active parts of the grids are located in one plane.

In Figure 3, the grid wires 24 are shown thicker than the wires 22 of the other grid.

As shown in Figures 3 and 5, the active parts of the grids may also have a more circular section.

As an alternative, it is possible to use a directly heated cathode and in this case, if this cathode is mounted in zigzag fashion, the gridshape shown in Figure 3 is highly advantageous.

Although only two forms of construction are shown in the figures, it is obvious that the grids may be constructed in many difierent ways.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode and an anode, and a pair of control electrodes positioned between the cathode and anode and lying in the same surface, an input circuit having one side connected to the control electrodes, a fixed resistor and a variable resistor connected in series between said cathode and the other side of said input circuit, and a connection between one of said control electrodes and a point between the fixed resistor and the variable resistor.

2. An electron discharge device having a cathode and an anode, and a pair of control electrodes having portions interleaved and lying in the same surface, an input circuit, each of said control grids being connected to one and the same side of said input circuit, a fixed resistor and a variable resistor connected in series between the cathode and the other side of said in-.

put circuit, and a connection between one of said control electrodes and the point between the fixed resistor and variable resistor.

3. An electron discharge device having a cathode and an anode surrounding said cathode, and a pair of coaxial control electrodes surrounding and positioned between the cathode and the anode, said control electrodes comprising grids, the turns of which are interposed and lie in the same surfaces equally distant from the cathode, an input circuit, each of said control electrodes being connected to one and the same side of said input circuit, a fixed resistor and a variable resistor connected in series between the cathode and the other side of said input circuit, and a conection between one of the control grids and a point between the fixed resistor and variable resistor.

4. An electron discharge device having a cathode and an anode surrounding said cathode, and a pair of coaxial control electrodes surrounding and positioned between the cathode and the anode, said control electrodes comprising grids, the turns of which are interposed and lie in the same surfaces equally distant from the cathode, an

input circuit, each of said control electrodes being connected to one and the same side of said input circuit, a fixed resistor and a variable resistor connected in series between the cathode and the other side of said input circuit, and a connection including a grid leak resistor between i one of the control grids and a point between the fixed resistor and variable resistor, and a grid leak resistor connected between the other of said control electrodes and the said other side of said input circuit.

5. An electron discharge device having a cathode and an anode surrounding said cathode, and a pair of coaxial control electrodes surrounding and positioned between the cathode and the anode, said control electrodes comprising grids, the

turns of which are interposed and lie in the same surfaces equally distant from the cathode, an input circuit, each of said control electrodes being connected to one and the same side of said input circuit, a fixed resistor and a variable resistor connected in series between the cathode and the other side of said input circuit, and a connection including a grid leak resistor between one of the control grids and a point between the fixed resistor and variable resistor, and a grid leak resistor connected between the other of said control electrodes and said other side of said input circuit, the diameter of the grid wires of one of said control grids being larger than the diameter of the grid wires of the other of said control grids.

J OHAN LODEW'IJK HENDRIK JONKER. 

